The reactivity of anti-M. paratuberculosis (specifically against p35 and p36 antigens) antibodies in a significant proportion of CD patients would suggest a causal role for the organism in CD.
The fact that sera from Crohn's disease patients reacted to p36 with the same high frequency as the sera from patients that were exposed to mycobacterial antigens further supports the hypothesis of the mycobacterial etiology in Crohn's disease.